The control and adaptation of transmit parameters on the link level generally include issues such as link adaptation and power control.
Link adaptation allows transmission parameters (normally modulation and coding scheme) used for communication to be adapted in order to optimally exploit the potential of the communication channel, usually to provide high data transfer rates along with low bit error rates.
Power control is used in numerous wireless systems to enable “efficient” communication without expending unnecessary power resources.
Because communicating devices, such as mobile devices or similar short-range communicating devices, in many instances are dependent on battery power there is a general need to minimize their energy consumption.
From an energy consumption perspective, low transfer rates at relatively high transmit power levels are of course undesirable since low rates translate into long transmit durations, which at high power translate into high energy consumption levels. On the other hand, it may not be possible to realize reliable communication at high transfer rates using low transmit power levels so low energy consumption is not always easy to realize.
In the technical field of multi-hop routing, which relates to communication between source and destination nodes along a route over several hops, traditional minimum power routing strives to ensure that the selected route minimizes accumulated link transmit power under the assumption of flexible power setting (and different path loss for each link), but a single fixed transmit duration common for all links.
It should also be understood that an energy or power consumption analysis limited to transmit power levels only considers the radiation-related energy consumption for transmitting information.
As concluded in reference [1], there is little practical information available about the energy consumption behavior of well-known wireless network interfaces, and device specifications do not normally provide information in a form that is helpful. Reference [1] describes a series of experiments that provide measurements of the energy consumption of an IEEE 802.11 wireless network interface operating in an ad hoc networking environment. The experimental data is presented as a collection of linear equations for calculating the energy consumed in sending, receiving and discarding broadcast and point-to-point data packets of various sizes. It is concluded in reference [1] that the energy consumption has a complex range of behaviors that are relevant to the design of network layer protocols.
There is indeed a general need for an improved strategy for controlling link transmit parameters for communication in a wireless communication network.